Just as the Sloths of the present day were formerly represented in the same geographical area by the gigantic Megatheroids, so the little banded and cuirassed Armadillos of South America were formerly represented by gigantic species, constituting the genus Glyptodon.  The Glyptodons (fig. 262) differed from the living Armadillos in having no bands in their armour, so that they must have been unable to roll themselves up.  It is rare at the present day to meet with any Armadillo over two or three feet in length; but the length of the Glyptodon clavipes, from the tip of the snout to the end of the tail, was more than nine feet.

[Illustration:  Fig. 261.—­Skeleton of Mylodon robustus.  Post-Pliocene, South America.]

[Illustration:  Fig. 262.—­Skeleton of Glyptodon clavipes.  Post-Pliocene, South America.]

There are no canine or incisor teeth in the Glyptodon, but there are eight molars on each side of each jaw, and the crowns of these are fluted and almost trilobed.  The head is covered by a helmet of bony plates, and the trunk was defended by an armour of almost hexagonal bony pieces united by sutures, and exhibiting special patterns of sculpturing in each species.  The tail was also defended by a similar armour, and the vertebrae were mostly fused together so as to form a cylindrical bony rod.  In addition to the above-mentioned forms, a number of other Edentate animals have been discovered by the researches of M. Lund in the Post-Pliocene deposits of the Brazilian bone-caves.  Amongst these are true Ant-eaters, Armadillos, and Sloths, many of them of gigantic size, and all specifically or generically distinct from existing forms.

Passing over the aquatic orders of the Sirenians and Cetaceans, we come next to the great group of the Hoofed Quadrupeds, the remains of which are very abundant in Post-Pliocene deposits both in Europe and North America.  Amongst the Odd-toed Ungulates the most important are the Rhinoceroses, of which three species are known to have existed in Europe during the Post-Pliocene period.  Two of these are the well-known Pliocene forms, the Rhinoceros Etruscus and the R.  Megarhinus still surviving in diminished numbers; but the most famous is the Rhinoceros tichorhinus (fig. 263), or so-called “Woolly Rhinoceros.”  This species is known not only by innumerable bones, but also by a carcass, at the time of its discovery complete, which was found embedded in the frozen soil of Siberia towards the close of last century, and which was partly saved from destruction by the exertions of the naturalist Pallas.  From this, we know that the Tichorhine Rhinoceros, like its associate the Mammoth, was provided with a coating of hair, and therefore was enabled to endure a more severe climate than any existing species.  The skin was not thrown into the folds which characterise most of the existing forms; and the technical name of the species refers to the fact